A Sewer Back-up Endorsement and an Overland Water Endorsement are two very different types of coverage. Sewer Back-up covers damage caused by the back-up of sewers, septic tanks, eaves troughs and downspouts. For example, it covers claims resulting from your toilets or taps overflowing into your home causing damage.
An Overland Water Endorsement covers damage from water entering your home from the ground level. This includes overland water from melting snow, torrential rain and the overflow of river banks.